alexvoste
44 lines
1.4 KiB
C
44 lines
1.4 KiB
C
#ifndef SPINLOCK_H
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#define SPINLOCK_H
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#include <stdint.h>
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typedef struct {
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volatile uint32_t ticket;
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volatile uint32_t serving;
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} spinlock_t;
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#define SPINLOCK_INIT { .ticket = 0, .serving = 0 }
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static inline void spinlock_acquire(spinlock_t* lock) {
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uint32_t my_ticket = __atomic_fetch_add(&lock->ticket, 1, __ATOMIC_RELAXED);
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while (__atomic_load_n(&lock->serving, __ATOMIC_ACQUIRE) != my_ticket)
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asm volatile("pause");
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}
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static inline void spinlock_release(spinlock_t* lock) {
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__atomic_fetch_add(&lock->serving, 1, __ATOMIC_RELEASE);
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}
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static inline int spinlock_try_acquire(spinlock_t* lock) {
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uint32_t serving = __atomic_load_n(&lock->serving, __ATOMIC_RELAXED);
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uint32_t ticket = __atomic_load_n(&lock->ticket, __ATOMIC_RELAXED);
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if (serving != ticket) return 0;
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uint32_t expected = serving;
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return __atomic_compare_exchange_n(&lock->ticket, &expected, serving + 1,
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0, __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
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}
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static inline uint64_t spinlock_acquire_irqsave(spinlock_t* lock) {
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uint64_t flags;
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asm volatile("pushfq; pop %0; cli" : "=r"(flags) :: "memory");
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spinlock_acquire(lock);
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return flags;
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}
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static inline void spinlock_release_irqrestore(spinlock_t* lock, uint64_t flags) {
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spinlock_release(lock);
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asm volatile("push %0; popfq" :: "r"(flags) : "memory", "cc");
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}
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#endif |